Electronic Counter Measure (ECM) systems generally operate over a large range of frequencies, for example, between the VHF frequency band and K frequency band (i.e., according to the IEEE radio bands). These systems are typically divided into a plurality of sub-systems, each operating on a corresponding frequency range and packaged separately. For example, the ALQ-99 system is housed in five different pods. Furthermore, this multiplicity of sub-systems results in substantial power consumption. One of the sub-systems in an ECM system may be a signal re-transmitting system. Retransmitting signals toward the direction from which signals are received (i.e., either the same signals or other signals) may increase the Signal-to-Noise Ration (SNR) of the retransmitted signal. Another application of retransmitting signals toward the direction from which signals are received is in ECM systems. For example, interfering with signals transmitted by a RADAR allows a vehicle (e.g., aircrafts, vessels, land vehicles) to impair the detection of that vehicle and other vehicles by the RADAR. According to one known in the art method for interfering with RADAR signals the vehicle transmits a directional interfering signal, substantially similar to the RADAR signal, toward the RADAR. Since the directional interfering signal is substantially similar to the RADAR signal the RADAR cannot distinguish between the interfering signal and the RADAR signal reflected from the vehicle. Thus, the interfering signal ‘jams’ the RADAR signal. Transmitting a directional signal requires either using directional antennas (e.g., horn antennas) or using a phased antenna array, where the relative position of the antennas in the array is known.
U.S. Pat. No. 7,248,203 to Gounalis, entitled “System and Method for Detecting and Jamming Emitter Signals”, describes a detection system which includes one or more antenna and a processing systems that receive and process signals received by the antenna. These signals are, for example, electromagnetic signals transmitted in any one of a number of frequencies, including radar, communication, and other types of signals. The received signals are passed to the processor. The processor implements a scan strategy detecting one or more threats by observing frequency bands defined by the scan strategy. The system determines the scan strategy. The scan strategy is determined to optimize signal intercept of an selected sets of emitter or emitters parameters. The scan strategy is also determined to minimize the “dwells” for each emitter. A dwell defines the scan resources such as frequency range, scan period and revisit time. The processor determines emitter parameters according to the received signals in the determined “dwells”. The processor determines a jamming signal and provides this jamming signal to a jammer transmitter which “jams” the emitter.
U.S. Pat. No. 4,467,328 to Hacker, entitled “RADAR Jammer With an Antenna Array of Pseudo-Randomly Spaced Radiating Elements”, directs to a RADAR jammer which includes an antenna array with randomly spaced elements, a jammer transmitter, a power divider, and a plurality of phase shifting elements. The RADAR jammer further includes a directional finding system which includes four monopulse horn antennas, a monopulse receiver, a phase-shifter logic and phase-shifter drivers. The power divider is coupled with the jammer transmitter and with the phase shifting elements. The phase-shifter driver is coupled with the phase shifting elements and with the phase-shifter logic. The monopulse receiver is coupled with the four horn antennas and with the phase-shifter logic. The phase shifting elements are further coupled with the antenna array elements.
The monopulse receiver receives signals from the horn antennas and determines the direction of the detected threat and generates a signal representative of the threat direction. The phase-shifter has values of the spacing of the antenna array elements stored thereat (i.e., the spacing dimensions of the randomly distributed antenna elements are known) and determines a set of phase shifting signals intended to alter the phase of the power signals of the radiation elements to render a single narrow high power beam of jamming radiation directed at the detected threat. Because of the spread-out nature of the radiating elements, it is proposed that the main beam will be much narrower and require much less energy to defeat the RADAR threat in the detected direction. As a result, the remaining energy associated with the spuriously produced beam is spread out over the entire threat volume dispersed everywhere.
U.S. Pat. No. 4,472,719, to Hills, entitled “ECM Multiple-Target Retrodirective Antenna” directs to a receive and transmit linear antennas arrays each including a plurality of antenna elements. Each antenna element is mounted in a horizontal plane and connected via an equal length transmission line to a microwave. The microwave lens consists of two parallel conducting surfaces spaced less than half a wavelength apart. Each output port of the microwave lens corresponds to an individual beam pattern in azimuth. A logic processor converts the voltages from each receiver to binary voltage. The binary voltages are gated to a switching apparatus which receives ECM signals from an external source. The logic processor detects the signal and activates the switch to transmit the signal according to the desired beam.